Improvement in bridges



wwwes NPETERS, PKOTKLLITHOGQAPHER. WASHINGTON D C with w iggggggghm JAMES B; E'ADS, or ST. Louis, MISSOURI.-

Letters item No. 83.942, dated Nooember 10, 1868.

IMPROVEMENT IN BRIDGES.

The Schedule referred. to in these Letters Patent and making part of the lame.

To all whom it may concern.-

Be it known that I, J AMJES B. Enns, of St. Louis, in the county of St. Louis, and State of Missouri, have invented a new and useful Improvement in the Gonstruction of Bridges; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in the art to make and use the same, reference being had tothe accompanying drawing, forming a part of this specification.

This invention relates to a new and useful improve. month the construction of metallic arch-bridges, as hereinaiter fully shown and described, whereby a strong and substantial bridge is obtained with a comparatively light weight of metal.

The accompanying drawing- Figure 1, represents a side view of my invention, and

Figure 2, a diagram, showing'a modification of the same.

A A represent the abutments of the bridge, constructed in the usual or any proper'manner, and B is the arch at one side of the bridge, which may be jointed or made continuous from abutment to abutment, the dimensions of the arches being commensurate with the length of the span, and their ends resting on and secured to the abutments in any proper manner.

0 0 represent rods which are secured at one end in the abutments A A, and extend longitudinally over the arches B to their centres or crowns, two rods, 0 0, being at each side of each half of the arch, or two rods for each arch will answer, and said rods may be forked at their ends to admit two pairs of levers, D, being applied to form the connection.

These rods are connected to these arches by the bent levers D D, which are secured to the arches by their fulcrum-pins or bolts .a.

The lower arms of these levers are connected by segmentrgears b, or other equivalenttneans, and the tops of the upper arms connected to the rods 0 C by. pivot-bolts c. These levers thus form a compensating joint to relieve the rods of the strains created by temperature.

' The spandrels of the bridge (the portions included between the arches B and the rods 0) may be braced by rods d, which may have a vertical or inclined positioh, or both; or the rods C may be trussed, as shown in the drawing, and. designated by E, each truss extending half the length of the span, and connected at the compensating joint described, in such a manner as to admit of the necessaryexpansion and contraction of the rods The eifect or a load at M will-be to straighten that part of the arch immediately beneath it, and move the centre of the arch towards the unloaded portion, which latter portion will be bulged upward, as indicated by the red line.

If the centre of the arch be prevented from moving horizontally, this straightening of the loaded side and bulging up of the other side of the arch will be prevented. g

This movement is resisted by the rods 0, in consequence of the connection of the 'rods 0 U with each other and the arch, the direction of this force against the rods being indicated by the arrows 1.

The object of the spandrel-bracing or o,the trussing of the rods will be to distribute the client of the partial load'over the entire arch.

These braces will resist the descent of that part of the curve which is loaded, and the upward tendency of the part that is unloaded, and by securing the centre of the arch from moving horizontally, the'result will be similar to that of dividing the whole arch into two arches of half the span, thus greatly lessening the amount of trussing or spandrel-bracing that would be required if the centre of the arch were free to move horizontally.

By this arrangement a strong and substantial bridge may be obtained with much less weight of metal.

The effects of temperature upon metals prevent them from being used to resist the horizontal movement of the crown of the arch, by throwing the strain against the abutments in a horizontal direction, unless some compensating device, such as I have described, be used to take up the expansion and relieve the abutments of the thrust created by increase of tempera ture, and to relieve them of the reverse strain created by their contraction under the effect of cold.

\ The method described, of rods and levers, is not only applicable to upright arches, but also to suspended or inverted arches; and it may be used to secure the haunches of the arch from movement, by the use of a compensating joint placed at each hannch, and connected together by a central rod from one to the other, and two side rods from the joints to the abutments. These joints may be made simply with a vertical lever, pivoted at its centre to the arch, and having its two arms of equal or proper lengths, and each end pivoted to its respective rod as shown in the diagram, fig. 2.

In the latter case, if the central rod is longer than the united length of the two side rods, the arms of the levers to which it will be united should be proportionq ally longer than the arms to which the short rods will be secured, as its expansion will be greater than that of the short rods. p The single vertical lever, shown in this diagram, is

also applicable at the crown of the arch, instead ofthe two bent levers first described.

I do not confine myself to any particular mode of bracing or trussin g the arches B, or spandrels, for various plans may be devised for that purpose Having thus described my invention,

What I claim as new, and desire to secure by Let ters Patent, is-

The levers D, forming a compensating expansionjoint, with the horizontal members 0, for the purpose of preventing the horizontal movement of the arch under the effect oil a moving load on the bridge, when constructed and-arranged as herein described.

J AS. B. EADS.

Witnesses:

FRANK BLOOKLEY, ALEX. F. Rosnn'rs, 

